The brothers, who jointly chair developer giant Sun Hung Kai Properties, and Hong Kong's former chief secretary Rafael Hui were arrested and charged in a major swoop by the city's anti-graft watchdog in July.

They were accused by the watchdog of bribing Hui, who held the government's second-highest position and is the most senior official ever arrested for graft.

Their not guilty plea was entered after the prosecution dropped one of the three charges against the younger brother, Raymond, which alleged he conspired to offer an advantage to Hui.

Speaking in Cantonese alongside two other accused, all five told magistrates that they pleaded not guilty. The court then agreed to shift the trial to the high court.

"You are now committed to the Court of First Instance for trial," Magistrate Li Kwok-wai said, before he adjourned the hearing.

A trial date is yet to be fixed and the prosecution has said previously that they intend to call 72 witnesses. They maintain their two charges against Thomas Kwok and eight against Hui.

It is a case that has gripped Hong Kong as the Kwoks own some of its most iconic real estate -- Sun Hung Kai is the city's biggest property developer, based on market capitalisation.

The Kwoks have an estimated family wealth of US$20 billion, according to Forbes magazine.

Analysts said the case reinforced public suspicion that officials were in the pockets of Beijing-backed business elites, who control everything from ports to telecommunications and even supermarkets in Hong Kong.